Electric furnace.



C. A. KELLER.

ELECTRIC FURNACE.

APPLICATION FILED rzmzs. 1904.

Patented Mar, 7, 1911.

CHARLES ALBERT KELLER. OF PARIS, FRANCE.

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Specification of Letters Patent.

Patented Mar. '7, 1911.

Application filed February 26, 1904. Serial No. 195,324.

To all whom it may concern:

Be it known that I, CHARLES ALBERT KEL- LER, a citizen of the'Republic of France, and a resident of N0. 3 Rue Vignon, Paris, in France, engineer, have invented certain new and useful Improvements in and Relating to Electric Furnaces, of which the following is a specification.

This invention relates. to an electrical furnace having a plurality of hearths connected by one or more channels adapted to receive fluid metal which isreduced at and flows from each hearth, the channel or chan nels being arranged preferably below the level of fusion of the materials in the different hearths, and being so placed that the electrical current can, at any given moment, be closed so as to pass through its or their contents.

3 a longitudinal section .illustrating the means for reheating described hereinafter. Fig. .4 1s a diagrammatlcal representatlon of the furnace, showing the electrical connections and indicating by arrows the directions of flow of the electric current.

In this furnace a strong electric current from. a dynamo or other suitable source of electricity enters by means ofmain con-. ductor B and shunt conductors l3 and B the vertically movable electrodes a, a, from ranged in the form of a cross and which will connect with a centrally disposed crucible cl which is'thus made very accessible. This arrangement. which is considered preferable is, however, only given as an example. It will be well understood that the system described requires at least two hearths;

The crucible d previously mentioned is ada ted to contain the materials according to the extent to which they have been melted inhearths c, c, c, a; they are thus kept heated the electric circuit is maintained as follows z-From generator A through conductor B, shunt conductors B and B to electrodes at and a respectively, from electrode a to electrode 1) through molten material in the direction of the arrow shown in the upperpart of crucible d in Fig. 4:, and simultaneously from electrode a to electrode 6 through the molten material in the direction of the arrow shown inthe lower part of crucible d in said figure, through electrodes b and b and shunt conductors C C respectively to main conductor C, and back to generator A. It will thus be understood that the electrodes at and a are of the same polarity, and the electrodes 6 and Z) are of opposite polarity to the electrodes at and a It should be observed here that, in such av system, when the tapping takes place, the electrical circuit could be broken by the withdrawal of the metal, as these materials serve as conductors connecting the hearths Y through which the current enters and leaves.

For the purpose of avoiding inconvenience in certain cases, whereby not only an entire stoppage of the function of the apparatus would be produced but also interference with the machines for generating the current, there may be provided between the two groups of hearths of different polarity electrical connections and between each two groups of hearths of like polarity electrical shunt connections are provided. For such purposethe bottom of each hearth is made of electrically conductivematerial 0'1 and they are connected with bars of copper, e, e, which connect the bottoms of each group of hearths, as shown in Fig. 2. That .is, one copper conductor 6 connects the bottoms of the hcarths c in which. the vertically movable electrodes a and a are disposed, and the other copper conductor a connects the bottoms of the heart'hs c in which the two electrodes of opposite polarity, namely electrodes Z) and Z are disposed. A. conductor 0' connects the two conductors e, e, as is shown in Figs. 1 and 3, and by-dotted lines in Fig. 2. Each of the conductors e, 'is

therefore divided into two approximately- Z), b, respectively, the current increasing in said conductors as the-resistance to the passage of the current in the fused mass becomes greater. The moment that the fused mass is insufficient toelectrically connect the materials which are being treated in the two groups of hearths of opposite polarity, the entire current will flow through the conductors e e e aforesaid. ,After the tapping the fused materials as they are reduced from hearths c, gather in canals f and crucible d, and part of the current begins to flow through the fused mass, inversely in proportion to the resistance in suchfused mass and conductors e e 6 When a sufficient mass of fluid metal has accumulated, the greater part of the current will pass through the said fluid mass, and only a part through conductors e e 6 it being understood that the use of the latter is only for the purpose of maintaining the passage of the current through the furnace after a tapping and to get the fusion of a fresh charge started. It will thereforebe understood that a portion of the current will always 'pass through the external conductors 6 e e, the current dividing inversely as the resistances of the fused mass and of the said external conductors. The putting back into the circuit of the fused mass connecting the hearths is thus automatic and progressive. Thus, there is no fear of irregularity or variation in the distribution of the electrical current.

The advantages of multiple hearth fur-- metal flows as it is being fused into the cen-,

- tral portion which as stated can be arranged in the form of a crucible and wherein the purification and refining can take place; the crucible can, for that purpose, be lined with a suitable composition. It is provided with a suitable opening for the introduction of proper additional material, and it may also be provided with a twyer t for the introduction of any suitable kind of gas, If such introduction into the body of the liquid.

produces an oxidizing action it.will not, in

consequence, consume the electrodes which are preferably'elongated and out 5f reach of the zone of introduction. Besides, a sample of the metal can easily be taken to determine the condition of the metal before pouring it.

The operation of the apparatus is as follows: The hearths, c, 0, are filled with material through a considerable portion of which the current flows. Considering for instance the treatment of iron ore a mixture of said ore, coke and flux will fill hearths 0, 0, a, 0. Under the action of the heat due to the passage of the electric current the fusing will take place, the fused metaltin each of the channels flowing-to its bottom and thenuniting in the crucible d which gradually fills up; the distribution of the electrical current then takes place as beforedescribed. To the fused mass which is more or less c'arbureted and which has gathered in the crucible d heat can be applied for the purpose of dephosphorization, and an oxidizing zone can be provided in the crucible into which air may be blown forthe purpose of refining.

When the metal in the crucible has been brought to the proper condition it is withdrawn by pourlng it.

In the case of treatment of copper ore, to

consider another case, the fusion of the metal will take place in each of the hearths c, 0', and the mass will become separated from the dross by gravity in the central crucible d into which air may be blown for the purpose of refining.

In the two cases cited the great industrial advantages will be noted which are to be gained by the use of a multiple hearth furnace due to the accessibility of the liquid mass.

In case the temperature of the liquid conthe direction of flow of the current whichhas entered said electrode h; in moving said electrode up and down, the passage ofthe current for reheating purposes can be easily regulated. When the electrode h isin use, it will be readily seen that a portion of the current will pass from'conductor B by means -v of the conductor B, through said electrode, and th'eg cu-rrent will then pass in the direction of the 'arrowsshown in crucible (Z (in Fig. 4:) to the hearths containing the electrodes b -and I).

Theuse of shunt conductors e, e, e referred to above, is. not absolutely necessary 'in' case the channels uniting the different oaive hcarths are horizontal, because in that case it can be arranged not, to withdraw the entire body of fused metal'by'pla'cing the hole for'such withdrawalat a certain elevation above the bottom of the crucible. The-invention also applies in the case where. the

materials conta ned in the crucible, while being conductors, are not sufficiently fluid to be" discharged by pouring. The metal in that case sim ly' serves as a conductor between the di erent hearths It will also be understood that the furnace escribed is also yery suitable for the employment of polyphase currents. if one hearth is used for each phase, and'the connections are suitably arranged I j This furnace tages for metallurgical operations can be emplofyed obtaining metals and-their alloys, or reducing as well as refining minerals, for the electrical manufacturing of glass, and in general for many other purof electric current, a conductor from the 'posi-' -tive pole ofsa'id source of current and c011- acent electrodes leading to the negative pole of said tially as described. j

' Copies of this patent may be obtained for poses, I claim 7 I j v. 1.. An electric furnace comprising a plu .rality of hearths, a crucible, arranged centrally of the liear'thsjliihannels connecting the crucible and each of-the hearths and so -arranged that each hearth is in communication with all oiithegother hearths, vertical electrodes arranged in each hearth, a-source nectedto. two adjacent electrodes, and a conductor connected to two adjacent electrodes oppositely disposed'to said first named adsource of electric current, substan- 2."An electricfurnacecomprising a plus rality of hearths, a1 crucible arranged in whichrofl'ers great advanproximity-fix each of the hearths, channels connecting-the crucible .and each of the hearths and so arranged that each hearth is v in communication with all of the other hearths, vertical electrodes arranged in each hearth, a vertical electrode arranged in the cruclble, a source of electric current, a conductor connected to two 'adjacent electrodes,

- said conductor being connected with the positive pole of-the source of the electric current, a similar conductor connected to two adjacent electrodes oppositely disposed to the first named and connecting with the negative pole of the source ofthe electric current, and a connection between the source of electric current and electrode arranged in the crucible, substantially as described.

3. An electric furnace comprising a plurality of hearths, acrucible arranged centrally of the hearths, channels connecting the crucible and each of the hearths-and soar-v ranged that each hearth is in communication with all of ,the other hearths, vertical electrodes arranged in each hearth, a source of an electric current, connections between two a'daeently disposed electrodes and the positive pole of the source of electric-current, conductors between the two adjacent hearths in which said adjacent electrodes are disposed. connecting with the two oppositely disposed adjacent hearths, and connections between two electrodes in said oppositely disposed hearths with the negative pole of said source I of electric current, substantially as-described.

In testimony whereof I have signed myname to this specification'in the presence. of two subscribin witnesses. CHAR ES ALBERT KELLER. Witnesses:

' PAUL' BAc rn,

JULIUS CAnsonn;

five cents each, by addressing" the Commissioner of Patents. Washington, "D. .0. 

